Float controlled pumping system for oil refineries



L. DE FLOREZ May 19, 1931.

FLOAT CONTROLLED PUMPING SYSTEM FOR OIL REFINERIES Original Filed Dec. 6. 1927 w M T A Patented May 19, 1931 UNITED STATES? PATENT OFFICE LUIB'DE 1140332, 01 POMIBE'I, CQNNEOTIOUT FLOAT CONTROLLED PUMPING SYSTEM FOR OIL anrnumms Substitute for application Serial No. 288,017, filed De'eeinber 8, 1927. This application filed March 17,

1980. Serial In certain oil refining operations, it is essential to the best results that the oil stream be kept continuously flowing and that a predetermined level be maintained in the container or containers. In the case of fractionating towers, the oil should be kept at a definite level in the bottom of the tower and should be removed in a continuous, though possibly varying stream, rather than by an o intermittent or interrupted flow. The hot oil pump which is usually provided at this point in the system is controlled in various ways to approximate these conditions, but so far as known, there has always been at best,

1 a mere approximation of these desired results. This pump is placed in various locations and at different distances from the tower, depending upon the particular form and requirements of the system, as re ards the course of the oil, relative location different parts of the apparatus,- etc., and hence cannot always be placed in the most eflective or most easily controlled situation.

These conditions have introduced certain 25 inaccuracies and faults and in particular, a

time element or lag, which at times may cause the pump to completely or practicall shut down and at other times to overrun itself in an effort to keep up with conditions r at the tower, permitting variations in level and producing interruptions or surges in oil flow, which are quite detrimental to the 'smooth action of the system, and which inv some cases have to be corrected or compensated for at other points in the system.

The objects of the present invention are to I) servo-'motor-type between a float or level governed device at the tower or container and a sensitive, accurate control for the power governor.

Other important novel features of the invention Wlll appear as the specification proceeds.

In the drawing accompanying and forming part of the specification, one practical embodiment of the invention is illustrated, but as this illustration is primarily for purposes of disclosure, it will be understood that changes and modifications may be made without departure from the true spirit and broad scope of the invention as hereinafter described and claimed.

The single view in the drawin is a broken sectional perspective and part y diagrammatic representation of an embodiment of the invention.

In this particular embodiment, there is a fractionatlng tower 1 in which it is desired to maintain a constant liquid level 2. To maintain this level, the oil is drawn off through a pipe line 3 bya hot oil pump 4 actuated b the steam engine 5. The motive fluid' for t is engine is governed by a throttle-valve 6.

The ener y for actuating the throttle-valve is furnished by a power governor shown in i the form of a piston 7 actuated by a link 8 connected with the valve rocker 9 of the engine and adapted to pump oil or other fluid to a cylinder 10 containing a pressure piston 11 connected by bell crank 12 and link 13 with the stem of the throttle-valve. The pressure piston is shown counterbalanced by an adjustable weight 14 and the fluid is shown as bypassed from the pressure cylinder by way of a passage 15 controlled by a fine throttle-valve 16'which is accurately regulatable to govern the action of the throttling piston. A highly sensitive control. is attained in the present disclosure by having the stem of this valve threaded into an ac'-.

curately formed screw seat 17 with a pitch such that a relatively fine movement will effect a definite, accurate controlling movement of the valve.

At the tower or container there is provided a float or level actuated device, the same being here shown as a solid, more or less buoyant member 18, carried by an arm 19 on a shaft 20 having a. bearin in the casing and rosion or the like, are avoided and the ad justable counterbalance permits corrections or variations in the position of the member 18 in the liquid to be readily made.

The sensitive liquid level device at the tower and the sensitive control for the power governor of the more or less remotely located hot oil pump, are connected by an instantaneously operating coupling shown as a servomotor set and comprising a generator or transmitter 23 at the tower and a receiver motor 24 at the power governor.

The transmitter and receiver are illustrated as duplicate servo-motorshaving their rotors 25 energized from a source of single phase current at 26, and their stators 27 connected by energizing wiring 28 so that the motor will instantly follow in step, the movements of the transmitter. The rotor of the transmitter is shown as having a direct coupling 29 with the float shaft and the rotor of the motor is shown as directly connected with the screw stem of the governor throttle by a pin and slot coupling 30. The throttle of the power governor is thus immediately subject to varlations in liquid level in the foot of the tower.

The governor throttle is of small size and hence freely actuated by the servo-motor to bring into operation the ample power of the governor to operate the main throttle or power supply control of the prime mover for the pump. Thus, a relatively delicate control is made capable of exercising a powerful, accurate and substantially instantaneous control over the pump. The pump, therefore, res onds to variations ractically as soon as t ey are manifest an can continue in carrying off a more or less normal outflow without sudden variations. Surges and interruptions in flow are thus practically overcome and eliminated and the level is maintained within quite fine limits.

A visual indication is afforded in the illustration by. the provision of a pointer 31 positioned by the receiving motor and registering on a scale 32, which may be graduated in terms of throttle-opening, pump speeds, liquid level, liquid flow, or the like.

Ordinarily and preferably the regulator for the power governor will be initially set, as indicated, to maintain what may be called a predetermined normal speed of action of the pump for what are known to be the normal flow conditions of the system, so that it will be in a condition to fully and instantly take care" of the fluctuations to both sides of this so-called normal condition.

To provide for any relative adjustments that may be necessary or desirable as between the transmitter and motor and as between these two devices and the mechanisms with which they are connected, the couplings 29 and 30 are indicated as adjustable in character, the body of the coupling 29 being shown as a sleeve 33 secured in adjustable relation on the shaft 34 of the transmitter by set screw 35 and the body of the coupling 30 being shown as a sleeve 36, secured in adjustable re-.

lation on the shaft 37 of the receiver motor by set screw 38. These constructions, it will be seen make it possible to set the transmitter and receiver motor in diflerent'relations to each other, to set the transmitter with respect to the level device and to set the receiver with respect to the power governor or mechanism which it actuates or controls.

Another method of effecting the liquid level control is b regulating a valve in the take-off line 3. his valve may be controlled from the motor either directly or through the intermediacy of the power relays The latter condition is illustrated, the valve being shown at 39, actuated from the power relay by a link 40 connected with the arm 12 of the relay and with a suitable lever 41 on the stem of the valve. This. take-off valve regulation may be used in con'unction with the pump regulation, or as will be understood, one may be used independently of or without the other.

The power relay may be governed in other ways than by means of the small throttle, for instance, by shifting the weight 14 on the arm 12, this being done by suitable mechanical connections from the motor 24, in which event it might be possible to make the-orifice at 16 constant. The float device might operate in a smaller supplementary tank connected at the roper level with the main tank, as will be rea ily understood.

The transmitter and receiver motors being properly set or adjusted by the adjustable couplings 29, 30, with respect to each other and the first with respect to the float and the second with respect to the control for the power overnor, it will be seen that variations in liquld level in the container will effect immediate and corresponding variations at the.

power governor. The float on the end of the lever 19 rocks the shaft 20 and consequently the rotor 25 connected with said shaft. The receiver motor 24, even though located at some relatively remote point more convenient and accessible to the power governor and power mechanism, through the electrical connections between, is motivated in step with the transmitter motor. Consequently, v'ai iations at the float even though relatively small are converted into substantially corresponding or proportional adjustments at the bypass throttle 16 of the power governor. The force of the power governor is therefore-accurately regulated to vary the throttle 6 of the pump engine 5 as may be required to keep the pump running at just the right speed to maintain the level substantially constant and the oil circulation substantially smooth and continuous. stant action of the apparatus any changes in flow are made gradually and smoothly rather than suddenly or by steps or jerks.

The float operates at practically no load and therefore is free to respond to the slightest variation in liquid level. The leverage of the float arm in respect to the transmitter is also a factor in the so-called free operation of the liquid level detecting and transmitting mechanism. All the real work of governing the pump is performed by the power governor, which has ample power to operate the throttle valve 6, or the liquid flow valve 39, or both. This power governor however is sensitive to the small control valve 16, which is easily turned by the receiving motor 24. It follows from this that there is always ample power to effect control of the pump and that this power is immediately controlled one way or the other by the governor valve, which is so small and light that it is freely actuated b the receiving motor. Thus there is practica 1y no lag at any point in the line of transmission from the float to the final flow control mechanism. Transmission fromfloattoreceivmg motoris substantially 1nstantaneous,ample power is always present in the power governor to shift the flow control mechanism and the control of the powergovernor is so light and sensitive that the receiving motor is fully able to efiect such control and it therefore freel responds to the transmitter motor.

Wliile the invention is .of particular importance in connection with the control of fractionatin towers, it has other uses, as will appear to t ose skilled in the art and the claims following should be construed accordin l TV hat is claimed is:

a controller by which, operation of said pow Because of the sensitive and in-' which rising and falling movements of liquid level in the container are imparted to the transmitter, a synchronously operating electrical receiver motor at the power governor and connected to operate the controller of said power governor and electrical connections from the transmitter at-the container to the receiver at the power governor, whereby variations in liquid level in the container are instantly translated into accurate control of the power governor for effecting corrective regulation of the pump necessary to keep the liquid level and circulation substantially constant, irrespective of the distance of the power governor from the container.

2. In apparatus of the character disclosed, the combination with a liquid container in which it is desired to maintain a normal liquid level and a pump connected with said container and by which the liquid level in the container is governed, of means for maintaining said liquid level within close limits and for, preserving the pump flow substantially continuous, smooth and as nearly even as possible, comprising a power governor for regulating the speed of the pump and having a controller by which operation of said power governor may be accurately determined, an electrical transmitter at the container, a shaft connected for operating said transmitter, a lever arm connected with said shaft and disposed within the container, a float member connected with said lever and by which rising and falling movements of liquidlevel in the container are imparted to the transmitter, a synchronously operating electrical receiver motor at the power governor and connected to operate the controller of said power governor; electrical connections from the transmitter at the container to the receiver at the power governor, whereby variations in liquid level in the container are instantly translated into accurate control of the ower governor for effecting corrective regu ation of the pump necessary to keep the liquid level and circulation substantially constant, irrespective of the distance of the power governor from the container, and adjustable coupling means between the float and transmitter and between the receiver motor and power governor controller for enabling independent setting of the transmitter and receiver with respect to each other and with respect to the float mechanism and the power governor controller.

3. In apparatus of the character disclosed,

the combination with a liquid container in which it is desired to maintain a normal liquid level and flow means connected to govcm the liquid level in said container, a power governor for regulating said flow means and provided with a controller by which operation of said ower governor may be accurately regulate an electrical transmitter at the container, a shaft connected for operating said transmitter and having a lever arm oper-' ating in the container, a float member carried by said lever arm and actuated by varying liquid levels to effect operation of the transmitter, a synchronously operating receiver motor at the power governor and connected to actuate the controller of said power governor and electrical connections extending from the transmitter at the container to the receiver motor at the power governor.

In testimony whereof I aifix my signature.

LUIS DE FLOIREZ. 

